1. Field of the Invention
The present invention relates to stable, painless gel preparations for the topical application of diclofenac sodium.
2. Description of the Prior Art
Diclofenac sodium is a derivative of phenylacetic acid, having the formula ##STR1## Diclofenac sodium is a non-steroid drug soluble in water and alcohols, and having excellent anti-inflammatory and analgetic effects. At the present time, it is used only in the form of oral preparations or suppositories exhibiting excellent anti-inflammatory and analgetic effects when so administered. However, side effects such as stomach and intestine problems, liver problems and kidney problems, may occur, especially upon oral administration. Therefore, anti-inflammatory and analgetic preparations which are absorbed cutaneously without showing such side effects are desired.
In this regard, a gel preparation for topical application containing indomethacin, a non-steroidal anti-inflammatory, is known (Japanese Patent Laid-open No. Sho 53(1978)-81616). However, this preparation is unstable, and possesses a yellow color (the color of indomethacin) which soils clothes.
Accordingly, it is among the objects of the present invention to provide topical formulations containing diclofenac sodium which are stable, which may be readily employed without pain or other side effects, and which do not soil clothing or have other undesirable characteristics.